package com.zs.security;

import com.auth0.jwt.JWTSigner;
import com.auth0.jwt.JWTVerifier;
import com.auth0.jwt.JWTVerifyException;
import com.auth0.jwt.internal.com.fasterxml.jackson.databind.ObjectMapper;
import com.zs.security.Exception.JWTExpiredException;

import java.io.IOException;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import java.security.SignatureException;
import java.util.HashMap;
import java.util.Map;

/**
 * Description:
 *
 * @author: zsq-1186
 * Date: 2017-08-22-11:27
 */
public class JWT {

    private static final String SECRET = "XX#$%()(#*!()!KL<><MQLMNQNQJQK sdfkjsdrow32234545fdf>?N<:{LWPW";

    private static final String EXP = "exp";

    private static final String PAYLOAD = "payload";

    //加密，传入一个对象和有效期
    public static <T> String sign(T object, long maxAge) {
        try {
            final JWTSigner signer = new JWTSigner(SECRET);
            final Map<String, Object> claims = new HashMap<String, Object>();
            ObjectMapper mapper = new ObjectMapper();
            String jsonString = mapper.writeValueAsString(object);
            claims.put(PAYLOAD, jsonString);
            claims.put(EXP, System.currentTimeMillis() + maxAge);
            return signer.sign(claims);
        } catch(Exception e) {
            return null;
        }
    }

    //解密，传入一个加密后的token字符串和解密后的类型
    public static<T> T unsign(String jwt, Class<T> classT) throws SignatureException, NoSuchAlgorithmException, JWTVerifyException, InvalidKeyException, IOException {
        final JWTVerifier verifier = new JWTVerifier(SECRET);

        final Map<String, Object> claims;

            claims = verifier.verify(jwt);
            if (claims.containsKey(EXP) && claims.containsKey(PAYLOAD)) {
                long exp = (Long) claims.get(EXP);
                long currentTimeMillis = System.currentTimeMillis();
                if (exp > currentTimeMillis) {
                    String json = (String) claims.get(PAYLOAD);
                    ObjectMapper objectMapper = new ObjectMapper();
                    return objectMapper.readValue(json, classT);
                }else {
                   throw new JWTExpiredException("token已经过期",currentTimeMillis-exp);
                }
            }


        return null;
    }

}
